I have a 66 with the stock drum breaks all around. Factory v8. i need to install a new master cylinder for a short time to get the vehicle on the road. which dual cylindr master cylinder will work.

I dont want to make it to complicated because i am swiching to disc in the nex couple of months

 

I believe a stock '67 m/c will work, although you may need to retain your original pushrod. The Napa # is UP 36251 (new), or TS 101378 (reman)

 

The master cylinder for a 1974 Maverick will bolt right in and comes with a new pushrod identical to the one in a 1966 Mustang.

The problem is that drum brakes use a different MC than disc/drum brakes, so if you are going to change over you will have to buy another MC.